The effect of high-energy electron irradiation on ZnO-based ohmic and Schottky contacts

A systematic study of radiation effects on the major parameters of ohmic and Schottky contacts based on n-ZnO is introduced. Al and Au metals were used as contact elements in order to fabricate the ohmic and Schottky structures, respectively. The transmission line method (TLM) measurements on Al/n-ZnO have revealed that high-energy (6, 9, 12 MeV) and relatively low-dose (3 × 1012 e- cm-2) electron irradiation produced lower specific ohmic contact resistivity values as compared with the reference sample. The current-voltage (I-V) and capacitance-voltage (C-V) measurements on the Au/n-ZnO structures are shown to increase in ideality and to decrease in the Schottky barrier heights with increasing electron energy. These findings have been interpreted based on the assumption that the atoms of the contact elements diffused into the semiconductor material, thus turning the rectifying character to ohmic behaviour with the influence of radiation-matter interaction and subsequent annealing effects. © 2006 IOP Publishing Ltd.